drifter_xs

car spec:
87 rx7 N/A
new oil
new plugs
new fuel pump and filter
new ING wires

for some reason when i drive my car it feels like i hit a hardcore rev limiter crazy hesitation and jerking at 4k RPM!! what may cause this?!

barkz

iTrader: (1)

did it happen randomly or have you done something right before it started?

satch

iTrader: (1)

Can you free rev the car in neutral past this supposed wall? When driving can you slowly pass the 4000 rpm level?

drifter_xs

i changed my trailing coil and leading coil cuz my car was all eff'ed up.

it will go past it slowly sometimes but when i try to give it more gas it jerks violently.

RotaryEvolution

iTrader: (30)

plug in your secondary injectors.

drifter_xs

lol they are plugged

RotaryEvolution

iTrader: (30)

check them again.

satch

iTrader: (1)

There are two wires for each injector plug. If either wire is pulled back within the plug then that injector won't work. Can you rev the car while idling to a rather high rpm?

drifter_xs

i cant. it kinda sounds like a throttle bounce. peaks at 4k then drops a few hundred and then bounces back up again and again and again

tps?

bumpstart

have you tried the search function.. its as easy as searching for 3800 rpm hesitation,, 15 billion threads on it .. its usually a fault in the loom crimps .. and the faulty crimps are about 25 cm up the loom from the ecu

satch

iTrader: (1)

If you cannot rev the car while idling in neutral past 4000 rpm then you can check your fuel pressure and you might want to remove the O2 sensor (unscrew it from its housing) so as to check and see if things change for the better.

RotaryEvolution

iTrader: (30)

not likely crimps if it is a california car, unless it came from an eastern state and driven through winters.

pull the secondary injector clips off and inspect the pins, tug the wires a little bit and see if any are pulling out. takes less than 5 minutes. if the engine was ever worked on MOST ALL of the time i see that people just yank off the connectors because they can't figure out the simple wire locking mechanism that holds them in place.

could be a plugged up cat like Satch is indicating but it wouldn't be a quick transition and the car would likely rev freely all the way to redline until put under a load.

the TPS wouldn't be faulty at a set RPM, it would be faulty at a certain throttle position.

fuel pressure would be the second place i would look outside the secondary injector clips. a plugged up fuel filter or dying pump will still allow the engine to run but it will start to run out of fuel when you load the engine up, especially when the injectors are transitioning at 3850 RPMs.

drifter_xs

lol here is a video to better explain what is going on. thanks bud

bumpstart

tps calibration/swap ..do this first

misterstyx69

iTrader: (142)

..uh guys...
https://www.rx7club.com/2nd-generati...-help-1009284/
OP has had electrical problems before.If anyone cares to check his other threads out,it may help get this problem ironed out!

drifter_xs

Thank you.

sbrmechanic

Its your secondary injectors, they either need to be replaces or the connections need to be cleaned, there is something called the "ground of death" which happened to me, you gotta pull the intake to get to it buts its worth it, unless you wanna rev half of what you could for the rest of your cars life

drifter_xs

Do you have a link to that thread? Thank you again

sbrmechanic

ya know, someone put the linkon my thread a couple months back and it reeally helped me out ill look for it

sbrmechanic

scope that:

https://www.rx7club.com/2nd-generati...tering-998575/

and make sure the electrical connections that plug directly into your injectors are good, one of my metal pieces came out so now its connected with a peice of paper clip, ghetto mechanics haha

rapidriver

iTrader: (2)

I agree. I had the same problem (different than the 3800 hesitation, feels more like a fuel cutoff) I was looking for fuel problems and tried many things before I calibrated the TPS. That fixed the problem.

Of course it could be any part of that circuit that's the problem... connections, the ecu, bad adjustment, or a bad TPS altogether. Make yourself a test light with about $10 in radioshack LEDs and terminals and hook up per the FSM. (There is a how to on here somewhere for it).

Once I adjusted it correctly... the problem disappeared. On another RX-7 the TPS would not calibrate to make the lights do what they should. I replaced this one and adjusted the new one in... again, problem gone.

87FCna

iTrader: (3)

Replace omp,ecu,tps at the same time.

RotaryEvolution

iTrader: (30)

replace the car while you're at it.

wthdidusay82

iTrader: (15)

That's not very nice. Any car can be fixed with patience, knowledge, and effort. The usual issue is money.

Jet-Lee

iTrader: (1)

Your trailing injectors might be wired backwards....check them.